The present invention relates to an occlusal plane analyzer, an articulator and an occlusal plane analyzing method used for analysis of occlusal planes and determination of occlusal planes in creating prosthetic appliances.
It is known that an occlusal plane constituted of continuous occlusal surfaces of teeth generally forms a spherical plane (Monson spherical plane) with a radius of 4 inches.
Broadrick occlusal plane analyzer is used as an occlusal plane analyzer for analyzing occlusal planes. As described in “The Journal of Dental Technics Extra Issue: Illustrative Basic Knowledge of Occlusion” edited by Takashi Imada, Ishiyaku Publishers, Inc., Jun. 30, 1984, p 118-121 and “The Journal of Dental Technics Extra Issue: Visual Basic Knowledge of Occlusion” edited by Katsuji Fujita, Ishiyaku Publishers, Inc., Jun. 25, 2002, p 102, in the Broadrick occlusal plane analyzer, first, 4-inch circular arcs from a distal angle section of a canine tooth and from a distal buccal cusp tip of a last molar or a condylar ball of an articulator are plotted with use of a compass on a flat plate held in the upper part of a lower jaw model to obtain an intersection thereof as an occlusal plane analysis point (a central point of Monson curve). Then, a 4-inch circular arc is plotted from the occlusal plane analysis point with use of the compasses on the lower jaw model, and this circular arc is used as an occlusal plane (occlusal curvature) constituted of connected tips of the buccal cusps. The Broadrick occlusal plane analyzer requires careful operation so as to prevent the fulcrum of the compass from shifting during drawing of the occlusal planes.
The occlusal plane analyzer can only show one point on the occlusal plane and it is not possible to intuitively check whether a plurality of teeth are arranged on the correct occlusal plane.
In Japanese Patent No. 3680139, JP 2003-190186 A and JP 2003-245291 A, occlusal plane analyzers are disclosed which have a rod provided above a jaw model, an arm with its one end connected to the upper end of the rod so as to be three-dimensionally rotatable, and a circular-arc nail provided on the other end of the arm, so that occlusal planes can easily be drawn with the tip of the nail. In these occlusal plane analyzers, it is necessary to adjust the fixed position of the jaw model and the position of the rod so that the rotation center of the arm on the upper end of the rod may be positioned in 4 inches from a distal angle section of a canine tooth and from a distal buccal cusp tip of a last molar of the jaw model or a condylar ball of an articulator, and this adjusting work is not easily achieved.